Serena Williams has been fined $17,000 (13,156) for the code violations she received during the US Open final, the United States Tennis Association (USTA) said on Sunday.
The United States and Britain had also called for China to provide proof of Peng's whereabouts.
Serena Williams was included on the entry list for the US Open on Wednesday along with fellow former champion Novak Djokovic, who will not be able to compete due to his refusal to be vaccinated against COVID-19.
The organisers of the US Open said they could have better communicated with wheelchair athletes before announcing they would not be part of this year's scaled-down event in New York and are now rethinking their decision.
Tennis fans 12 years or older will be required to show proof of a COVID-19 vaccine in order to attend the US Open, tournament officials announced Friday, just three days before the main draw was set to begin.
Serena Williams, who has dropped to 172nd in the world after being sidelined for almost a year with injury and illness, has opted to use an injury-protected ranking to gain entry into the US Open, the United States Tennis Association (USTA) said on Wednesday.
Novak Djokovic said he is preparing for the US Open as if he will be allowed to compete at the hardcourt major, despite his refusal to take the COVID-19 vaccine.
Andy Roddick has agreed to re-join the American Davis Cup team next year after missing a season, the United States Tennis Association (USTA) said on Thursday.
The 2003 US Open will be played at the USTA National Tennis Center in Flushing, New York, from August 25 to September 7.
The former US Open champion has withdrawn from this year's tournament because of a lingering wrist injury.
The respective world number ones were named as top seeds for next week's US Open.
47-year-old Martina Navratilova and Lisa Raymond were also picked in the U.S. team for their Fed Cup first-round tie against Slovenia.
The organisers of the US Open said on Thursday a decision on whether to hold the Grand Slam this year amid the coronavirus outbreak will be made in June, and playing it without fans is on the table but highly unlikely. The US Open, which is scheduled to run from August 31 to September 13, is both the largest and loudest of the four Grand Slam events on the tennis calendar and United States Tennis Association (USTA) chief executive Mike Dowse does not anticipate that changing.
Novak Djokovic posted black screenshots on his Twitter and Instagram pages with the message "Black Lives Matter", and was joined by Federer and Nadal, the other members of the "Big Three" of men's tennis.
The United States Tennis Association said on Tuesday that a non-player has tested positive for the virus within the controlled environment that will host the Western & Southern Open and the US Open in New York.
Tennis already sets the bar with equal prize money paid to women and men at Grand Slam tournaments
New York Governor Andrew Cuomo said the USTA would take "extraordinary precautions" to protect players, including robust testing, additional cleaning, extra locker room space and dedicated accommodation.
Russian and Belarusian players will be allowed to compete at the US Open this year but only as neutrals, the United States Tennis Association (USTA) announced on Tuesday.
Former world number one Novak Djokovic will miss the US Open after he said on Thursday that he will not be able to travel to New York for the tournament, having chosen not to be vaccinated against COVID-19.
Besides the athletes, the exemption applies to the sporting leagues' essential staff, spouses and dependents, the statement said.
Grand Slam champions Daniil Medvedev from Russia and Belarusian Victoria Azarenka will not be able to participate in the June 27-July 10 tournament.
Australian Paralympic tennis champion Dylan Alcott, who led the player backlash and had described the exclusion as 'disgusting discrimination', thanked organisers for reversing the decision.
As captain, the former world number one led the United States to a 10-8 record in World Group play, including a run to the semi-finals in 2012 and 2018, the latter which ended in a loss to Croatia 11 days ago.
Britain's Andy Murray expects some of the top male players to follow women's world number one Ash Barty in skipping next month's US Open in New York due to concerns over the coronavirus pandemic. Australian Barty said on Thursday she is not comfortable travelling to the United States amid the pandemic for the hardcourt Grand Slam, which begins on August 31.
Serena Williams was the runner-up in Flushing Meadows each of the past two years
There is a petition circulating to allow Novak Djokovic to play at the US Open but the Serbian appears likely to miss the entire North American hardcourt swing barring a sudden change in COVID-19 protocols in the United States and Canada.
France's Benoit Paire has tested positive for COVID-19 and pulled out of the US Open starting on Monday, French sports daily reported on Sunday. Paire, seeded 17th at the Grand Slam event, had been scheduled to play Poland's Kamil Majchrzak in the first round at Flushing Meadows on Tuesday.
Serena Williams' behaviour in Saturday's US Open final divided the tennis world after she called the chair umpire a "liar" and a "thief" and said he treated her differently than male players during her loss to Naomi Osaka.
'I hope that as an association we make the best decision for our business, for our health, for the tournaments, for public.'
American Sofia Kenin counter-punched her way back from a set down against Garbine Muguruza to win her first Grand Slam title at the Australian Open with a 4-6, 6-2, 6-2 win in Melbourne on Saturday.
Athletes will not feel 100% safe until a vaccine for the novel coronavirus is available and the US Open should only proceed if all qualified players are able to travel to the Grand Slam, American doubles specialist Rajeev Ram said. Professional tennis was suspended in early March as countries went into lockdown to contain the spread of the virus and the season will not resume until early August.
Wimbledon champion Garbine Muguruza suffered a 6-2, 6-4 defeat at the hands of unseeded Czech Barbora Strycova in the second round of the Nature Valley Classic in Birmingham on Thursday.
The Memorial Coliseum in Portland, Oregon, will host the November 30 - December 2 match.
Japan rallies to support Osaka after French Open withdrawal.
Serena Williams was unseeded at the French Open last month due to an extended absence for the birth of her first child but she is not likely to face the same problem at the US Open.
The French Tennis Federation, in a surprise move, switched the claycourt Grand Slam tournament to Sept. 20-Oct. 4 from its May start due to the novel coronavirus outbreak. The new Roland Garros dates clashed with the Sept. 25-27 Laver Cup. The tournament will now be held from Sept. 24-26 in 2021.
Tennis great and founder of the WTA Billie Jean King was among those who applauded the announcement.
